Heretofore, the opening and closing of windows has been based selectively on either the swing system or the slide system. Particularly, windows used for high-rise buildings include some which are constructed so that they cannot be opened beyond a certain degree to prevent falling, but such arrangement has a problem that sufficient ventilation is impossible.
Thus, there has been developed a bendable multiple window comprising two windows, upper and lower, connnected together using hinges so that they can be opened and closed along the connecting region. In such bendable multiple window, when it is bent open, the upper end of the upper window slides downward along guides on the lateral frames of a window attaching framework.
In such arrangement, when the two windows are opened by being bent, the opening presents a triangle when the windows are viewed from the side, which triangle, because of its shape, cannot be used as an emergency escape opening in case of a fire or the like. Another problem is that the size of the opening is sometimes not sufficient depending on the degree of pollution of the air in the room.